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/*
* This file is part of PowerDNS or dnsdist.
* Copyright -- PowerDNS.COM B.V. and its contributors
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of version 2 of the GNU General Public License as
* published by the Free Software Foundation.
*
* In addition, for the avoidance of any doubt, permission is granted to
* link this program with OpenSSL and to (re)distribute the binaries
* produced as the result of such linking.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <boost/version.hpp>
#if BOOST_VERSION >= 105400
#include <boost/container/static_vector.hpp>
#endif
#include "dnswriter.hh"
#include "misc.hh"
#include "dnsparser.hh"
#include <limits.h>
/* d_content: <---- d_stuff ---->
v d_truncatemarker
dnsheader | qname | qtype | qclass | {recordname| dnsrecordheader | record }
^ d_rollbackmarker ^ d_sor
*/
template <typename Container> GenericDNSPacketWriter<Container>::GenericDNSPacketWriter(Container& content, const DNSName& qname, uint16_t qtype, uint16_t qclass, uint8_t opcode)
: d_content(content), d_qname(qname), d_canonic(false), d_lowerCase(false)
{
d_content.clear();
dnsheader dnsheader;
memset(&dnsheader, 0, sizeof(dnsheader));
dnsheader.id=0;
dnsheader.qdcount=htons(1);
dnsheader.opcode=opcode;
const uint8_t* ptr=(const uint8_t*)&dnsheader;
d_content.reserve(sizeof(dnsheader) + qname.wirelength() + sizeof(qtype) + sizeof(qclass));
d_content.resize(sizeof(dnsheader));
uint8_t* dptr=(&*d_content.begin());
memcpy(dptr, ptr, sizeof(dnsheader));
d_namepositions.reserve(16);
xfrName(qname, false);
xfr16BitInt(qtype);
xfr16BitInt(qclass);
d_truncatemarker=d_content.size();
d_sor = 0;
d_rollbackmarker = 0;
}
template <typename Container> dnsheader* GenericDNSPacketWriter<Container>::getHeader()
{
return reinterpret_cast<dnsheader*>(&*d_content.begin());
}
template <typename Container> void GenericDNSPacketWriter<Container>::startRecord(const DNSName& name, uint16_t qtype, uint32_t ttl, uint16_t qclass, DNSResourceRecord::Place place, bool compress)
{
d_compress = compress;
commit();
d_rollbackmarker=d_content.size();
if(compress && !name.isRoot() && d_qname==name) { // don't do the whole label compression thing if we *know* we can get away with "see question" - except when compressing the root
static unsigned char marker[2]={0xc0, 0x0c};
d_content.insert(d_content.end(), (const char *) &marker[0], (const char *) &marker[2]);
}
else {
xfrName(name, compress);
}
xfr16BitInt(qtype);
xfr16BitInt(qclass);
xfr32BitInt(ttl);
xfr16BitInt(0); // this will be the record size
d_recordplace = place;
d_sor=d_content.size(); // this will remind us where to stuff the record size
}
template <typename Container> void GenericDNSPacketWriter<Container>::addOpt(const uint16_t udpsize, const uint16_t extRCode, const uint16_t ednsFlags, const optvect_t& options, const uint8_t version)
{
uint32_t ttl=0;
EDNS0Record stuff;
stuff.version = version;
stuff.extFlags = htons(ednsFlags);
/* RFC 6891 section 4 on the Extended RCode wire format
* EXTENDED-RCODE
* Forms the upper 8 bits of extended 12-bit RCODE (together with the
* 4 bits defined in [RFC1035]. Note that EXTENDED-RCODE value 0
* indicates that an unextended RCODE is in use (values 0 through 15).
*/
// XXX Should be check for extRCode > 1<<12 ?
stuff.extRCode = extRCode>>4;
if (extRCode != 0) { // As this trumps the existing RCODE
getHeader()->rcode = extRCode;
}
static_assert(sizeof(EDNS0Record) == sizeof(ttl), "sizeof(EDNS0Record) must match sizeof(ttl)");
memcpy(&ttl, &stuff, sizeof(stuff));
ttl=ntohl(ttl); // will be reversed later on
startRecord(g_rootdnsname, QType::OPT, ttl, udpsize, DNSResourceRecord::ADDITIONAL, false);
for(auto const &option : options) {
xfr16BitInt(option.first);
xfr16BitInt(option.second.length());
xfrBlob(option.second);
}
}
template <typename Container> void GenericDNSPacketWriter<Container>::xfr48BitInt(uint64_t val)
{
unsigned char bytes[6];
uint16_t theLeft = htons((val >> 32)&0xffffU);
uint32_t theRight = htonl(val & 0xffffffffU);
memcpy(bytes, (void*)&theLeft, sizeof(theLeft));
memcpy(bytes+2, (void*)&theRight, sizeof(theRight));
d_content.insert(d_content.end(), bytes, bytes + sizeof(bytes));
}
template <typename Container> void GenericDNSPacketWriter<Container>::xfrNodeOrLocatorID(const NodeOrLocatorID& val)
{
d_content.insert(d_content.end(), val.content, val.content + sizeof(val.content));
}
template <typename Container> void GenericDNSPacketWriter<Container>::xfr32BitInt(uint32_t val)
{
uint32_t rval=htonl(val);
uint8_t* ptr=reinterpret_cast<uint8_t*>(&rval);
d_content.insert(d_content.end(), ptr, ptr+4);
}
template <typename Container> void GenericDNSPacketWriter<Container>::xfr16BitInt(uint16_t val)
{
uint16_t rval=htons(val);
uint8_t* ptr=reinterpret_cast<uint8_t*>(&rval);
d_content.insert(d_content.end(), ptr, ptr+2);
}
template <typename Container> void GenericDNSPacketWriter<Container>::xfr8BitInt(uint8_t val)
{
d_content.push_back(val);
}
/* input:
if lenField is true
"" -> 0
"blah" -> 4blah
"blah" "blah" -> output 4blah4blah
"verylongstringlongerthan256....characters" \xffverylongstring\x23characters (autosplit)
"blah\"blah" -> 9blah"blah
"blah\97" -> 5blahb
if lenField is false
"blah" -> blah
"blah\"blah" -> blah"blah
*/
template <typename Container> void GenericDNSPacketWriter<Container>::xfrText(const string& text, bool, bool lenField)
{
if(text.empty()) {
d_content.push_back(0);
return;
}
vector<string> segments = segmentDNSText(text);
for(const string& str : segments) {
if(lenField)
d_content.push_back(str.length());
d_content.insert(d_content.end(), str.c_str(), str.c_str() + str.length());
}
}
template <typename Container> void GenericDNSPacketWriter<Container>::xfrUnquotedText(const string& text, bool lenField)
{
if(text.empty()) {
d_content.push_back(0);
return;
}
if(lenField)
d_content.push_back(text.length());
d_content.insert(d_content.end(), text.c_str(), text.c_str() + text.length());
}
static constexpr bool l_verbose=false;
static constexpr uint16_t maxCompressionOffset=16384;
template <typename Container> uint16_t GenericDNSPacketWriter<Container>::lookupName(const DNSName& name, uint16_t* matchLen)
{
// iterate over the written labels, see if we find a match
const auto& raw = name.getStorage();
/* name might be a.root-servers.net, we need to be able to benefit from finding:
b.root-servers.net, or even:
b\xc0\x0c
*/
unsigned int bestpos=0;
*matchLen=0;
#if BOOST_VERSION >= 105400
boost::container::static_vector<uint16_t, 34> nvect, pvect;
#else
vector<uint16_t> nvect, pvect;
#endif
try {
for(auto riter= raw.cbegin(); riter < raw.cend(); ) {
if(!*riter)
break;
nvect.push_back(riter - raw.cbegin());
riter+=*riter+1;
}
}
catch(std::bad_alloc& ba) {
if(l_verbose)
cout<<"Domain "<<name<<" too large to compress"<<endl;
return 0;
}
if(l_verbose) {
cout<<"Input vector for lookup "<<name<<": ";
for(const auto n : nvect)
cout << n<<" ";
cout<<endl;
cout<<makeHexDump(string(raw.c_str(), raw.c_str()+raw.size()))<<endl;
}
if(l_verbose)
cout<<"Have "<<d_namepositions.size()<<" to ponder"<<endl;
int counter=1;
for(auto p : d_namepositions) {
if(l_verbose) {
cout<<"Pos: "<<p<<", "<<d_content.size()<<endl;
DNSName pname((const char*)&d_content[0], d_content.size(), p, true); // only for debugging
cout<<"Looking at '"<<pname<<"' in packet at position "<<p<<"/"<<d_content.size()<<", option "<<counter<<"/"<<d_namepositions.size()<<endl;
++counter;
}
// memcmp here makes things _slower_
pvect.clear();
try {
for(auto iter = d_content.cbegin() + p; iter < d_content.cend();) {
uint8_t c=*iter;
if(l_verbose)
cout<<"Found label length: "<<(int)c<<endl;
if(c & 0xc0) {
uint16_t npos = 0x100*(c & (~0xc0)) + *++iter;
iter = d_content.begin() + npos;
if(l_verbose)
cout<<"Is compressed label to newpos "<<npos<<", going there"<<endl;
// check against going forward here
continue;
}
if(!c)
break;
auto offset = iter - d_content.cbegin();
if (offset >= maxCompressionOffset) break; // compression pointers cannot point here
pvect.push_back(offset);
iter+=*iter+1;
}
}
catch(std::bad_alloc& ba) {
if(l_verbose)
cout<<"Domain "<<name<<" too large to compress"<<endl;
continue;
}
if(l_verbose) {
cout<<"Packet vector: "<<endl;
for(const auto n : pvect)
cout << n<<" ";
cout<<endl;
}
auto niter=nvect.crbegin(), piter=pvect.crbegin();
unsigned int cmatchlen=1;
for(; niter != nvect.crend() && piter != pvect.crend(); ++niter, ++piter) {
// niter is an offset in raw, pvect an offset in packet
uint8_t nlen = raw[*niter], plen=d_content[*piter];
if(l_verbose)
cout<<"nlnen="<<(int)nlen<<", plen="<<(int)plen<<endl;
if(nlen != plen)
break;
if(strncasecmp(raw.c_str()+*niter+1, (const char*)&d_content[*piter]+1, nlen)) {
if(l_verbose)
cout<<"Mismatch: "<<string(raw.c_str()+*niter+1, raw.c_str()+*niter+nlen+1)<< " != "<<string((const char*)&d_content[*piter]+1, (const char*)&d_content[*piter]+nlen+1)<<endl;
break;
}
cmatchlen+=nlen+1;
if(cmatchlen == raw.length()) { // have matched all of it, can't improve
if(l_verbose)
cout<<"Stopping search, matched whole name"<<endl;
*matchLen = cmatchlen;
return *piter;
}
}
if(piter != pvect.crbegin() && *matchLen < cmatchlen) {
*matchLen = cmatchlen;
bestpos=*--piter;
}
}
return bestpos;
}
// this is the absolute hottest function in the pdns recursor
template <typename Container> void GenericDNSPacketWriter<Container>::xfrName(const DNSName& name, bool compress, bool)
{
if(l_verbose)
cout<<"Wants to write "<<name<<", compress="<<compress<<", canonic="<<d_canonic<<", LC="<<d_lowerCase<<endl;
if(d_canonic || d_lowerCase) // d_lowerCase implies canonic
compress=false;
if(name.empty() || name.isRoot()) { // for speed
d_content.push_back(0);
return;
}
uint16_t li=0;
uint16_t matchlen=0;
if(d_compress && compress && (li=lookupName(name, &matchlen)) && li < maxCompressionOffset) {
const auto& dns=name.getStorage();
if(l_verbose)
cout<<"Found a substring of "<<matchlen<<" bytes from the back, offset: "<<li<<", dnslen: "<<dns.size()<<endl;
// found a substring, if www.powerdns.com matched powerdns.com, we get back matchlen = 13
unsigned int pos=d_content.size();
if(pos < maxCompressionOffset && matchlen != dns.size()) {
if(l_verbose)
cout<<"Inserting pos "<<pos<<" for "<<name<<" for compressed case"<<endl;
d_namepositions.push_back(pos);
}
if(l_verbose)
cout<<"Going to write unique part: '"<<makeHexDump(string(dns.c_str(), dns.c_str() + dns.size() - matchlen)) <<"'"<<endl;
d_content.insert(d_content.end(), (const unsigned char*)dns.c_str(), (const unsigned char*)dns.c_str() + dns.size() - matchlen);
uint16_t offset=li;
offset|=0xc000;
d_content.push_back((char)(offset >> 8));
d_content.push_back((char)(offset & 0xff));
}
else {
unsigned int pos=d_content.size();
if(l_verbose)
cout<<"Found nothing, we are at pos "<<pos<<", inserting whole name"<<endl;
if(pos < maxCompressionOffset) {
if(l_verbose)
cout<<"Inserting pos "<<pos<<" for "<<name<<" for uncompressed case"<<endl;
d_namepositions.push_back(pos);
}
std::unique_ptr<DNSName> lc;
if(d_lowerCase)
lc = make_unique<DNSName>(name.makeLowerCase());
const DNSName::string_t& raw = (lc ? *lc : name).getStorage();
if(l_verbose)
cout<<"Writing out the whole thing "<<makeHexDump(string(raw.c_str(), raw.c_str() + raw.length()))<<endl;
d_content.insert(d_content.end(), raw.c_str(), raw.c_str() + raw.size());
}
}
template <typename Container> void GenericDNSPacketWriter<Container>::xfrBlob(const string& blob, int )
{
const uint8_t* ptr=reinterpret_cast<const uint8_t*>(blob.c_str());
d_content.insert(d_content.end(), ptr, ptr+blob.size());
}
template <typename Container> void GenericDNSPacketWriter<Container>::xfrBlob(const std::vector<uint8_t>& blob)
{
d_content.insert(d_content.end(), blob.begin(), blob.end());
}
template <typename Container> void GenericDNSPacketWriter<Container>::xfrBlobNoSpaces(const string& blob, int )
{
xfrBlob(blob);
}
template <typename Container> void GenericDNSPacketWriter<Container>::xfrHexBlob(const string& blob, bool keepReading)
{
xfrBlob(blob);
}
template <typename Container> void GenericDNSPacketWriter<Container>::xfrSvcParamKeyVals(const std::set<SvcParam> &kvs)
{
for (auto const ¶m : kvs) {
// Key first!
xfr16BitInt(param.getKey());
switch (param.getKey())
{
case SvcParam::mandatory:
xfr16BitInt(2 * param.getMandatory().size());
for (auto const &m: param.getMandatory()) {
xfr16BitInt(m);
}
break;
case SvcParam::alpn:
{
uint16_t totalSize = param.getALPN().size(); // All 1 octet size headers for each value
for (auto const &a : param.getALPN()) {
totalSize += a.length();
}
xfr16BitInt(totalSize);
for (auto const &a : param.getALPN()) {
xfrUnquotedText(a, true); // will add the 1-byte length field
}
break;
}
case SvcParam::no_default_alpn:
xfr16BitInt(0); // no size :)
break;
case SvcParam::port:
xfr16BitInt(2); // size
xfr16BitInt(param.getPort());
break;
case SvcParam::ipv4hint:
xfr16BitInt(param.getIPHints().size() * 4); // size
for (auto a: param.getIPHints()) {
xfrCAWithoutPort(param.getKey(), a);
}
break;
case SvcParam::ipv6hint:
xfr16BitInt(param.getIPHints().size() * 16); // size
for (auto a: param.getIPHints()) {
xfrCAWithoutPort(param.getKey(), a);
}
break;
case SvcParam::ech:
xfr16BitInt(param.getECH().size()); // size
xfrBlobNoSpaces(param.getECH());
break;
default:
xfr16BitInt(param.getValue().size());
xfrBlob(param.getValue());
break;
}
}
}
// call __before commit__
template <typename Container> void GenericDNSPacketWriter<Container>::getRecordPayload(string& records)
{
records.assign(d_content.begin() + d_sor, d_content.end());
}
template <typename Container> uint32_t GenericDNSPacketWriter<Container>::size() const
{
return d_content.size();
}
template <typename Container> void GenericDNSPacketWriter<Container>::rollback()
{
d_content.resize(d_rollbackmarker);
d_sor = 0;
}
template <typename Container> void GenericDNSPacketWriter<Container>::truncate()
{
d_content.resize(d_truncatemarker);
dnsheader* dh=reinterpret_cast<dnsheader*>( &*d_content.begin());
dh->ancount = dh->nscount = dh->arcount = 0;
}
template <typename Container> void GenericDNSPacketWriter<Container>::commit()
{
if(!d_sor)
return;
uint16_t rlen = d_content.size() - d_sor;
d_content[d_sor-2]=rlen >> 8;
d_content[d_sor-1]=rlen & 0xff;
d_sor=0;
dnsheader* dh=reinterpret_cast<dnsheader*>( &*d_content.begin());
switch(d_recordplace) {
case DNSResourceRecord::QUESTION:
dh->qdcount = htons(ntohs(dh->qdcount) + 1);
break;
case DNSResourceRecord::ANSWER:
dh->ancount = htons(ntohs(dh->ancount) + 1);
break;
case DNSResourceRecord::AUTHORITY:
dh->nscount = htons(ntohs(dh->nscount) + 1);
break;
case DNSResourceRecord::ADDITIONAL:
dh->arcount = htons(ntohs(dh->arcount) + 1);
break;
}
}
template <typename Container> size_t GenericDNSPacketWriter<Container>::getSizeWithOpts(const optvect_t& options) const
{
size_t result = size() + /* root */ 1 + DNS_TYPE_SIZE + DNS_CLASS_SIZE + DNS_TTL_SIZE + DNS_RDLENGTH_SIZE;
for(auto const &option : options) {
result += 4;
result += option.second.size();
}
return result;
}
template class GenericDNSPacketWriter<std::vector<uint8_t>>;
#include "noinitvector.hh"
template class GenericDNSPacketWriter<PacketBuffer>;
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